Trees, part 2: What’s in a tree?

Beyond being an integral part of a scenic view, trees benefit pedestrians in more ways than they are recognize for – largely because these helps are often unseen.

Are trees really that important? Tree roots can cause cracks and rises in sidewalks, which are dangerous for pedestrians. They are often “in the way” of “needed” land development. They can fall on houses during storms. They can easily catch fire. If beauty were their only quality, it may seem like trees just aren’t worth having around – they are more hazardous than helpful!

Yet, they are more than just shade against the sun, and they are more than just natural wonders. Older trees store carbon, and it takes decades for a tree to get to begin sequestering a measurable amount. Trees also have gigantic roots systems: much like icebergs, the majority of the tree is 2 to 3 times what you see in their canopy. Without this massive underground network, soil shifting would be of landslide proportions every time there was even a little rain. Trees actually do the job of what we know as “sewer” systems – that is, the drainage systems that simply whisk all water (and anything and everything else found on the increasing amount of impervious surfaces like asphalt and concrete) from storms away without discriminating pollutants like trees would.

Additionally, while tree roots can cause raised or uneven sidewalks, so can shifting soil. The sprawling spindles of a tree’s root system holds said soil in place – a necessity for a soggy city such as Seattle. In fact, there are many benefits for pedestrians in having trees around. Tree canopies protect from the sun, wind and rain: more pleasant than applying oily sunscreen, lighter than a windbreaker, easier than carrying an umbrella. Trees reduce toxins: trees that are closer to streets absorb nearly nine times more pollutants than trees located farther away and reduce the harm to human health caused by exhaust. With asthma and other chronic lung conditions on the rise (especially in children), this is no small consideration for those whose main form of transportation is their own legs.

Blacktop (asphalt) and concrete raise surrounding air temperatures by three to seven degrees, which means higher electric bills for air-conditioning and fan users. A strategically planted tree will provide enough shade to reduce energy bills 15 to 35%. This could mean a circa $0.66/sq.ft. savings from a well-shaded street vs. an unshaded street. And this could translate to over $23,00 over a 30-year period. Properly placed trees also shield pedestrians from traffic both with their own bodies and by calling for planting zones around them, creating an infrastructure of security by distancing walkers and joggers from fast-moving vehicles.

The list of benefits pedestrians get from trees goes on. While a tree may misplace a root too close to the underside of a sidewalk, the way they can help goes, like their roots, go largely unseen.